Vehicle windshield cleaning system

ABSTRACT

Apparatus and method for providing a heated cleaning fluid to a vehicle surface. The apparatus has an inlet port for receiving an amount of fluid; an outlet port for dispensing an amount of heated fluid; a heating element coil or tube covered with a plastic sheath that heats up fluid passing from the inlet to the outlet; and a control circuit for energizing at least a portion of the heating element with a voltage to heat the fluid passing from the inlet to the outlet. The apparatus also has expandable and compressible features and parts for protection against freezing.

RELATE BACK

The present invention is a continuation in part of co-pendingapplication Ser. No. 11/341,116 filed Jan. 27, 2006 which is acontinuation in part of application Ser. No. 10/894,266, filed Jul. 19,2004 (claiming priority from provisional application 60/551,571), whichis a continuation in part of application Ser. No. 10/653,827 filed onSep. 3, 2003, now U.S. Pat. No. 6,902,118 which is a continuation inpart of U.S. Ser. No. 10/269,647 filed Oct. 11, 2002 (claiming priorityfrom U.S. provisional application 60/415,552), now U.S. Pat. No.6,851,624, all of which are incorporated herein by reference and fromwhich priority is claimed.

FIELD OF THE INVENTION

The present invention concerns a windshield cleaning system, and moreparticularly to a windshield cleaning system that heats cleaning fluidapplied to the windshield.

BACKGROUND ART

U.S. Pat. No. 6,364,010 entitled “Device to Provide Heated Washer Fluid”to Richman et al. concerns an apparatus and method for improving thecleaning and deicing effectiveness of a washer fluid in a motor vehiclebefore spraying it against a windshield, headlamps, etc, and utilizesthe heat from the engine coolant to elevate the temperature of thewasher fluid. U.S. Pat. Nos. 5,957,384 and 6,032,324 also concernde-icing of a windshield.

SUMMARY OF THE INVENTION

The invention concerns apparatus and method for providing a large amountof heated cleaning fluid to a vehicle surface. A system constructed withan exemplary embodiment of the invention has an inlet port for receivingan amount of fluid; an outlet port for dispensing an amount of heatedfluid; a heating element that heats up fluid passing from the inlet tothe outlet; and a control circuit for energizing at least a portion ofthe heating element with a voltage to heat the fluid passing from theinlet to the outlet.

In one exemplary embodiment, the system provides heated cleaning fluidto a vehicle surface and includes structure defining an inlet port forreceiving an amount of fluid, an outlet port in fluid communication withthe reservoir for dispensing an amount of heated fluid; and a metalheating coil for heating fluid that passes from the inlet to the outlet.The exemplary heater coil is covered by an elastic material forcontaining fluid in the event of a ruptured heating element caused byone or more freeze/thaw expansion and contraction cycles. A controlcircuit for energizing at least a portion of the metal heating coil witha voltage to heat the heating element and the fluid passing from theinlet to the outlet.

In accordance with another feature apparatus for providing a heatedcleaning fluid to a motor vehicle surface includes a heating vesselhaving an interior and an inlet and outlet port. Heating fluid passesfrom the inlet to the outlet through the vessel. A controller has anenergizing component for heating fluid passing from the inlet to theoutlet, and an integral wiper motor control for actuating a motorvehicle surface wiper.

These and other objects advantages and features of the invention willbecome better understood from the following detailed description of oneexemplary embodiment of the present invention which is described inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematic of a representative system for usewith the present invention;

FIG. 1 a is an alternate block diagram schematic of a representativesystem for use with the present invention;

FIG. 2 is a perspective view of an embodiment of the invention showing aheating assembly without an outside housing;

FIG. 3 is a perspective view of the FIG. 2 embodiment of the inventionwith a housing in place;

FIG. 4 is a schematic diagram of a drive circuit coupled to a fluidheating element that forms part of the FIG. 2 heating assembly;

FIG. 5 is a perspective view of an alternative heating element from theheating element depicted in FIG. 2;

FIG. 6 is a perspective view of an alternative heating element from theheating element depicted in FIG. 2;

FIG. 7 is a perspective view of a heating assembly coupled to a fluidpump;

FIG. 8 is a sectional view of a heating assembly including the heatingelement illustrated by FIG. 6;

FIG. 9 is a sectional view of a heating assembly including the heatingelement illustrated in FIG. 11 and a freeze expansion feature;

FIG. 10 is a perspective view of a heating assembly including theheating element illustrated in FIG. 11, and a freeze expansion featureincluding a freeze expansion boot and a freeze expansion boot clamp;

FIG. 11 is a perspective view of top portion of the heating assembly ofFIG. 10;

FIG. 12 is a perspective view of a heating assembly housing;

FIG. 13 is a front elevation view of the heating assembly housing ofFIG. 12;

FIG. 14 is a side elevation view of the heating assembly housing of FIG.12; and

FIG. 15 is a top plan view of the heating assembly housing of FIG. 12;

FIG. 16 is a schematic depiction of a vehicle system with a long fluidflow path to a spray nozzle location;

FIG. 17 is a perspective view of another embodiment of a washer controlsystem;

FIGS. 18 and 19 are front and back elevation views of the FIG. 17embodiment of a washer control system that addresses concerns aboutexcessive fluid pressure drop caused by flow through a continuous heatercoil;

FIG. 20 is a top plan view of the washer control system of FIG. 17 witha top cover removed;

FIG. 21 is a schematic depiction of another alternate embodiment of awasher control system where a heating element is integrated into a fluidbottle on a motor vehicle; and

FIG. 22 is an alternate depiction showing a simplified flow diagram forthe structure of FIG. 18.

FIG. 23 is a sectional view of a heating assembly with dual heatingcoils constructed in accordance with an additional embodiment of theinvention;

FIG. 24 is a sectional view of a heating assembly including a submergedheater wire and a freeze expansion feature;

FIG. 25 is a projected top view of the heating assembly depicted in FIG.23;

FIG. 26 is a projected top view of the heating assembly depicted insectional view FIG. 27 of a heating assembly with dual coils constructedin accordance with an additional embodiment of the invention;

FIG. 27 is a projected top view of the heating assembly depicted in FIG.26.

FIG. 28 is an isometric view of a heating assembly with dual coilsconstructed in accordance with an additional embodiment of theinvention;

FIG. 29 is a sectional view of the heating assembly shown in FIG. 28;

FIG. 30 is a sectional view of the heating assembly shown in FIG. 28;

FIG. 31 is an end sectional view of a heating assembly shown in FIG. 28;

FIG. 32 is an end sectional view of a heating assembly shown in FIG. 28;

FIGS. 33 a and 33 b are schematic depictions of control circuits for usewith a washer control system constructed according to an alternativeembodiment of the present invention;

FIG. 34 is a schematic depiction of a control circuit for use with awasher control system constructed according to an alternative embodimentof the present invention;

FIG. 35 is a front perspective view of a washer control systemconstructed according to an embodiment of the present invention;

FIG. 36 is a rear perspective view of the washer control system of FIG.34;

FIG. 37 is a side perspective view of the washer control system of FIG.34;

FIG. 38 is a perspective view of an end cap component used in the washercontrol system of FIG. 34;

FIG. 39 is a section view of washer control system showing heater coilscovered with an elastic material constructed according to an alternateembodiment of FIG. 24;

FIG. 40 depicts an alternate embodiment of washer control system;

FIG. 41 is a rear perspective view of the washer control system withcover removed;

FIG. 42 is a front perspective view of the washer control system withcover removed; FIG. 43 is a section view of heater coil constructedaccording to an alternate embodiment with fluid internal and external tothe heater;

FIG. 44 is a partially section view of a control wherein probes sensealcohol content of washer fluid; and

FIG. 45-47 schematically illustrate an integrated heater/wiper controlsystem in accordance with one embodiment of the intention

FIG. 48 shows a wiper drive assembly including a motor with integralwasher pump further integrated with a washer fluid heater forming awiper, washer, heater system;

FIG. 49 detailed drawing of pump components and wiper motor components;

FIG. 50 is a partially section view of a wiper, washer, heater system;

FIG. 51 shows a system similar to that described in FIG. 49 but for asingle wiper arm such as what would be found on the rear window of anSUV or a minivan.

EXEMPLARY EMBODIMENT FOR PRACTICING THE INVENTION

The drawings depict embodiments of the present invention that concern awasher control system 10 for use with a vehicle. In the disclosedexemplary embodiments of the invention, the control system 10 is used inconjunction with a windshield washer apparatus. The control system 10includes a control circuit 14 that includes an electronic output drivesignal circuit 20 and an input signal interpretation or conditioningcircuit 16.

The input signal interpretation circuit 16 electronically interfaceswith at least one temperature sensor 18. In one embodiment of theinvention, the temperature sensor provides output signals related to thetemperature of the washer fluid supplied to windshield spray nozzles onthe vehicle. In one embodiment of the invention, the control system alsoincludes an electronic output circuit that drives output power controlfor at least one heating element 30 that applies heat to the windshieldwasher fluid. The illustrated module output is a “low side” type drive,meaning the module activates and deactivates the heater element bycontrolling the electrical circuit path to ground. In accordance with analternate control system, an electronic output coupled to a vehicularcommunication bus makes available data for system diagnostics. Analternate control system could have an output drive that is a “highside” type. Another alternate control system could have both “high side”and “low side” type drives working together as illustrated in FIG. 1 a.

The control circuit 14 includes a programmable controller 14 a thatimplements control algorithms for washer heater control output functionsin response to vehicle input signals. As seen in the functionalschematic of FIG. 1, the control system 10 includes an electronic output12 from the control circuit 14 for providing controlled current to theheating element 30. The control circuit 14 also includes an input signalinterpretation circuit 16, or interface, to monitor input signals from,as one example, the temperature sensor 18. The temperature sensor 18provides signals that allow for control of the amount of power deliveredto the heating element 30. The controller monitors inputs from a vehiclebattery 40 and vehicle ignition 42. In accordance with an alternateembodiment, the controller also monitors ambient temperature by means ofthe temperature sensor 19. In accordance with another alternateembodiment as illustrated in functional schematic of FIG. 1 a, thecontroller also monitors a user input and drives a vehicle washer fluidpump 45 a (FIG. 7) having a pump motor 117.

The control system also includes an electronic output circuit 20 tocontrol power coupled to at least one heater element 30. In theembodiment, the heater element 30 heats windshield washer fluid as thefluid passes through the heating element 30. A heating element thatwindshield washer fluid flows through, rather than a heating elementthat is submersed in the washer fluid, minimizes the formation and/orsize of mineral deposits that could potentially clog application nozzles37. The illustrated heating element 30 includes a length of stainlesssteel tubing with electrical connections 60, 62 (FIG. 2) electricallycoupled to ends of the tubing. The use of a stainless steel heatingelement, instead of a heating element made from another material such asaluminum, also minimizes the formation of nozzle clogging mineraldeposits. For example, an aluminum reservoir exposed to an air pocket ordissolved oxygen might be susceptible to oxidation. After the aluminumoxides form to some depth, the washer fluid could act to break off thealuminum oxide. The aluminum oxide particles could flow to the nozzle,causing a clog. Agitation during movement of the vehicle would alsocause pieces of the aluminum oxide to break off and flow to the nozzle37.

As seen in the Figures the system has an inlet 32 and an outlet 34. Theinlet receives washer fluid from a fluid reservoir 35 (FIG. 7) of amotor vehicle and the outlet 34 delivers heated washer fluid to nozzles37 mounted to the vehicle which direct the washer fluid against thevehicle surface, typically a windshield, lamp etc. The heating element30 can be constructed from other metals such as brass and the likehaving electrical resistivity properties such that they sufficientlyresist current flow to generate the required heat. In FIG. 2 a stainlesssteel tube is shown coiled to reduce the overall size of the heatingsystem. Alternative embodiments could have the heater element in otherbent or un-bent shapes such as serpentine or straight tubeconfigurations. The heating element of FIG. 2 has an uncoiled length ofapproximately 4 to 5 feet and is constructed of 5/16 inch diameterstainless steel tubing. When coiled to the configuration shown in FIG. 2the coiled heating element has an inside diameter of 1 11/16 inch.

FIGS. 6 and 7 depict another embodiment of a heating element 101 made upof a central reservoir 103 and a serially connected coiled heater tube104. A fluid tight engagement between the reservoir 103 and the coiledheater tube is accomplished by coupling the tube and the reservoir bysilver soldering or welding. Fluid is routed from vehicle reservoir 35through flexible tubing 300 into the central reservoir 103 by means ofan electrically conductive coupling. In one embodiment, a centralreservoir 103 is constructed from a length of copper tubing and has anouter diameter of approximately 1½ inches. Alternately, the centralreservoir could be constructed from brass, stainless steel or otherelectrically conductive materials. In this embodiment, the centralreservoir is constructed from stainless steel.

It is realized that the more resistive the material, the more resistanceheating will occur, adding to the heating of fluid in the centralreservoir. For example, a stainless steel central reservoir is moreresistive and would provide more heating. The coiled heater tube 104 isconstructed of stainless steel having a 5/16 inch diameter. The smallerdiameter tube 104 is connected to an outlet 34 that routes heated fluidto nozzles or the like. This outer tube is coiled to an inside diameterof 1 11/16 inches.

In the illustrated embodiment, an energizing signal is applied to theends of the series connected central reservoir 103 and heater tube 104so that current passes through both the reservoir 103 and the tube 104.When the coiled heater tube 104 is made from stainless steel and thecentral reservoir 103 is made from copper, the stainless steel coiledheater tube 104 has a higher resistivity than the copper centralreservoir 103 and therefore heats to a higher temperature more quickly,and acts as the primary heating source. In this example, the innerlarger diameter reservoir is heated by some resistance heating butmainly by conduction heating from the coil.

The reservoir 103 and heater tube 104 in this embodiment are thermallycoupled by an encapsulant 105 (see FIG. 8) within the housing to providesecondary heating of the reservoir 103 by the heater tube 104. Bothelements in this embodiment are surrounded by insulation within thehousing 50. The insulation could be air, foam, or potting encapsulant,however air is preferred. It is well known that air is a poor conductorof heat, making it an excellent insulator to prevent heat from escapingand cold from conducting in. One suitable encapsulant 105 is S7252commercially available from Epic Resins.

The thermal coupling of potting encapsulant 105 between reservoir 103and heater tube 104, along with the insulating feature already describedprovides additional advantages. In addition to being thermallyconductive, another function of the encapsulant 105 is heat retention,so that sustained heating of the reservoir 103 occurs when electricalenergy is not being applied to the heater tube 14. When surrounded bythe previously mentioned insulation, the thermal energy of encapsulant105 is maintained for extended periods of time. The thermal resistanceof encapsulant 105 has an effect on how quickly the heater tube comes totemperature and how quickly the reservoir is heated through conduction.If an encapsulant is chosen with a lower thermal resistance, heat fromthe heater will quickly be dissipated into the potting and hence morequickly into the reservoir. This will give an operator of the system alonger initial heating time of the smaller volume of fluid contained inthe tube, but faster heating of the larger volume of fluid contained inthe reservoir. Conversely, an encapsulant could be chosen with a higherthermal resistance. The higher thermal resistance encapsulant will notdissipate heat from the heater as quickly as an encapsulant of lowthermal resistance does thus allowing the heater to rise in temperaturefaster. This will provide an operator of the system with a shorterinitial heating time of the smaller volume of fluid contained in thetube, but a slower heating of the larger volume of fluid contained inthe reservoir. The thermal transfer properties of a commerciallyavailable encapsulant can be modified by additives or fillers resultingin a desirable thermal communication medium

The distance between the heater and the reservoir will have a similareffect on the heating of the heater tube and the reservoir. A lesserdistance between the heater and the reservoir will have a similarheating effect as a lower thermal resistance encapsulant and a greaterdistance between the heater and the reservoir will have a similarheating effect as a higher thermal resistance encapsulant. In addition,the reservoir construction material and its thickness contribute to thethermal transfer characteristics.

FIGS. 9 and 10 depict an embodiment of control system 10 with heatingelement 309. A reservoir 310 is in fluid communication with the inletport 312 for storing a reserve of fluid. The reservoir 310 employs anexpandable portion 314 at the bottom to protect the reservoir 310 fromdamage in the event that water freezes in the reservoir. An expandableboot 320 is made from a thermoplastic such as Neoprene or Santoprene™and covers an open end of the reservoir 310. One suitable boot isconstructed from Santoprene™ 201-55 available from Advanced ElastomerSystems, 388 S. Main St., Akron, Ohio 44311. It is held in place by acircumferentially extending clamp 321 similar to a hose clamp. Anoutwardly extending lip 323 of the reservoir impedes slippage of theclamp and securely holds the boot in place.

The durometer rating of the thermoplastic rubber for the boot 320 ischosen to ensure that the boot has minimal expansion during normal usageof the washer system. This is because if a material is chosen that hassignificant expansion and contraction during normal washer usage, thenozzles will continue to weep fluid after the pump has been turned offas the system pressure is equalized to atmosphere. However, the selectedmaterial should not be so hard that it does not allow the material toflex when frozen liquid pushes on it. This could cause material fatigueand fracture in metallic components. The selected material should remainstiff during high temperature exposure and not take a set, and shouldremain pliable enough under low temperature exposure to adequatelycompensate for the expansion of liquid/solid matter.

Referring to FIG. 3, the embodiments of FIGS. 8 and 9 are packaged in ahousing that is located in the engine compartment of the vehicle.Flanges 52 extend from sides of the housing 50 to allow the housing tobe attached to a wall of the vehicle engine compartment in oneembodiment. FIG. 7 shows an alternate attachment method using a bandclamp 53 with a mounting tab. Although there are other methods availablefor heating fluid, the embodiment of the invention as described above isadvantageous for heating a given volume of fluid rapidly. The relativelyhigh surface area of the heater compared to the volume of fluid beingsurrounded makes rapid fluid heating possible. Also, in this embodiment,fluid is being forced into the heater tube, where the fluid is thenresident for a given period of time sufficient to heat it to the desiredtemperature.

FIG. 5 illustrates a deicing system 31 for use with a vehicle. Apparatusof the system has an inlet port for receiving a fluid; an outlet portfor dispensing a heated fluid; an electrically conductive tube made upof two parts 33, 36 connected by a coupling 38 for delivering fluidbetween the inlet port and the outlet port for heating fluid passingthrough the tube from the inlet to the outlet. A control circuitenergizes opposite ends of the coiled tube with a voltage to heat thetube and the fluid passing through the tube. See issued U.S. Pat. No.6,851,624 (incorporated herein by reference) for additional details.

The programmable controller 14 constructed in accordance with theexemplary embodiment of the invention also implements control algorithmsfor washer heater control output functions in response to vehicle inputsignals. As washer fluid temperature changes due to ambient temperaturechanges, battery voltage changes, and the like, the amount of appliedheat is increased or decreased in order to maintain a washer fluid at ornear a target temperature.

Controller Schematics

The system block diagram shown in FIGS. 11 a, 45 and 46 depict operationof the control system 10.

The block diagram shown in FIG. 1 and the more detailed schematic ofFIG. 4 depict operation of a control system 10 having externalelectrical connections, which include Battery 40, Ground 44, andIgnition 42. The system block diagram 111 shown in FIG. 1 a showsfurther external electrical connections including a user operated CleanSwitch 113 and an output 115 to drive a vehicle washer pump motor 117.The Battery input connection 40 provides the voltage supply needed bythe control system 10. This connection allows the high current flowrequired by the heating element. The Ground connection 44 provides thecurrent return path to the battery negative terminal. This groundconnection allows the high current flow required by the heating elementplus the requirement of the control system 10. A fuse 55 (FIG. 6) islocated in series with the battery connection and the heater element. AnIgnition input 42 provides power to the controller. The battery voltageis monitored by the controller 14 to determine if there is sufficientvoltage present to allow the control system to operate.

An input 102 from the temperature sensor 18 in physical contact with theheating element 30 is directly related to washer fluid temperature.Washer fluid temperature is monitored by using a temperature sensor suchas a thermistor, RTD, or the like. The washer fluid is monitorednon-invasively by attaching the temperature sensor to the stainlesssteel tube of the heater. The temperature of the tube corresponds to thetemperature of the fluid within the tube. Alternatively, the fluidtemperature could be monitored invasively by placing a temperaturesensor directly into the fluid through a threaded fitting or othersuitable attachment method.

Operation

The controller receives a wake-up command signal from the Ignition input100 (FIG. 4). When the Ignition input is above a predetermined voltage,the controller 14 drives the heater element 30, the series connectedtubes of the heater 31 depicted in FIG. 5 or the reservoir and tube ofthe heater 101 low if the following are true:

-   -   1. The ignition voltage is greater than a first predetermined        level and less than a second predetermined level.    -   2. The sensed Heater element temperature is less than a        predetermined level.        Cleaning the windshield with warmed fluid can be accomplished by        the following:    -   1. Turning to FIGS. 1 a, 45 and 46:        -   a. Application of ignition 42 will cause the unit to heat            the volume of fluid. During the heating time an indicator            LED 119 flashes. The LED is shown as part of the clean            switch 113, but a skilled artisan could move the indicator            external to the switch.        -   b. When the indicator lamp is illuminated (not flashing),            momentarily activating the clean switch 113, initiates a            smart mode consisting of the energization of a washer pump            and wiper motor.        -   c. Output 115 activates the washer pump 117 to dispense            fluid on the windshield. In the embodiment shown in FIG. 45,            an external controller 123 activates a wiper motor 121 in            response to a signal from the washer switch 113. One skilled            in the art could have the same controller 14′ activate the            wiper motor 121 and the washer pump 117 this embodiment is            illustrated schematically in FIG. 46.        -   d. Hot fluid will be sprayed on the windshield and the            windshield wipers will cycle automatically, when the hot            fluid reduces to a predetermined temperature, output 115            deactivates, thus completing the smart mode and washer            spray/wiper cycling will halt. Momentarily pressing clean            switch 113 during the smart mode will cancel the operation.    -   2. With ignition 42 applied and when indicator 119 is        illuminated (not flashing) indicating warm fluid is available,        the activation of the existing vehicle wash switch will dispense        fluid for as long as the switch is closed for on-demand        cleaning.    -   3. The activation of the existing vehicle wash switch will        dispense fluid for as long as the switch is closed for on-demand        cleaning regardless of fluid temperature.

An output driver 20 depicted in FIG. 1 and FIG. 1 a applies power to theheater after starting the heating cycle. The output driver will thenbegin applying power to the heater at a rate of one hundred cycles persecond by means of a pulse width modulated (PWM) output to maintain thetemperature of the fluid. The fuse 55 is located between the batteryconnection and the heater element external to the housing 50 in theillustrated embodiment as shown in FIG. 6. An alternative embodimentcould have the fuse internal to the housing as shown in FIG. 1. In theexemplary embodiment of the invention, the desired heater temperature ispredetermined to be in a range between 120 and 150 degrees Fahrenheit.Placing the temperature sensor 18 in physical contact with the heatingelement and maintaining the heater temperature at a temperature at orbelow 150 degrees Fahrenheit prevents the heating element from heatingthe cleaning fluid to an undesirable temperature, such as boiling. Thishelps prevent the formation of mineral deposits that could potentiallyclog the nozzle 37. If the temperature sensor is not mounted directly onthe heating element, but is rather located in the fluid reservoir, onlyan approximate, latent measurement of the heating element temperature issensed. This would allow the heating element to heat to a temperaturethat is hotter than the desired fluid temperature and potentially causethe formation of nozzle clogging mineral deposits. The output driver 20will remain active as long as the ignition voltage is above apredetermined voltage and the heater temperature is below the desiredheater temperature as determined by the temperature sensor 18. When theignition is turned off, the controller is deactivated.

Turning now to FIG. 4, the output circuit 20 is depicted in greaterdetail. A heater connection 60 is shown in the upper right hand portionof the FIG. 4 depiction. This connection is grounded by means ofinitiating conduction of two power Field Effect Transistors (FET) 110,112 which provide a current path to ground from the heater connection 60to the ground connection 44 through a pair of reverse polarityprotection FET transistors 114, 116. The two transistors 110, 112 areturned on or rendered conductive by means of a pre-drive transistor 120that is coupled to an output 122 from the microprocessor controller 14a. First consider a high output from the controller 14 a at this output122. This turns on transistor 120 that pulls an input 124 of a totempole transistor combination 126 low. This signal turns on a lower of thetwo transistors of the totem pole combination to send activation signalthat turns off the two FETs 110, 112.

When the controller provides a low output from the controller 14 a atthe output 122, the transistor 120 turns off and pulls an input 124 to atotem pole transistor combination 126 high. This signal turns on anuppermost of the two transistors of the totem pole combination to sendan activation signal that turns on the two FETs 110, 112.

In one embodiment, a comparator 140 monitors current through thetransistors 114, 116 (and by inference the transistors 110, 112) anddeactivates the transistors in the event too high a current is sensed. Afive volt signal that is supplied at an input 142 from a power supply(FIG. 1) provides a reference input 144 to the comparator 140. When thenon-reference input exceeds the reference input due to a rise in thecurrent through the transistors 110, 112 (and associated rise in thevoltage across the transistors 114, 116) the output 146 of thecomparator goes low and removes the input from the gate of the FETs 110,112 that causes them to conduct. This low signal at the output 146 isalso coupled to the controller so that the controller can respond to theover current condition.

In accordance with the exemplary embodiment of the invention athermistor temperature sensor 18 is also coupled to the controller. Asignal at a junction between the temperature sensor 18 and a resistorcoupled to the five volt input 142 generates a signal at an input 150related to the temperature of the heater 30.

Referring to FIG. 2, in one embodiment, the control circuit 14 ismounted to a printed circuit board 160 supported by a cover 50 a of thehousing. As seen in FIG. 2, the illustrated connector 60 is a bentmetallic member that attaches to the heating element 30 in the vicinityof the printed circuit board 160 and is in physical contact with thecircuit components on the printed circuit board. The connector 60thereby not only acts as a path to ground for current passing throughthe heating element 30 but acts as a heat sink that transmits heat awayfrom the printed circuit board to the tube of the heating element 30 inthe region of the inlet where the reservoir pump 45 a routes cleaningfluid into the tube. Once the connections to the heating element havebeen completed, the housing 50 is attached to the cover 50 a and a foamcore material is placed into the housing. The material acts as aninsulator to impede heat loss from the outer surface of the heatingelement.

The exemplary control circuit includes a microcontroller running at aninternal clock frequency of 4.0 Megahertz. In the exemplary embodiment,the microcontroller 14 a selectively energizes the heating element basedon a voltage applied to the control circuit. This voltage may be thebattery voltage and/or the ignition voltage. When the ignition inputvoltage goes high, the control circuit will power up, come out of reset,and wait for a start delay time imposed by the controller to allow thevehicle's electrical system to become stable. After this start delay,the control circuit monitors the ignition voltage to determine if theignition is above a minimum enable voltage. A temperature signal fromthe sensor 18 is also monitored to see if the temperature of the fluidis below a set point temperature. The output drive feedback signal isalso monitored to ensure that the output is in the correct state. If allconditions are such that the output can be enabled, the output 122 tothe transistor 120 is pulled low. This initiates fluid heating.Initially, the output drive is on 100% for a maximum on time or untilthe feedback temperature reading approaches a set point temperature. Inone embodiment, a preset maximum on time is empirically derived to staybelow the boiling point of the cleaning fluid. Subsequently the controlwill read the heating tube temperature and make a determination if powershould be reapplied to the tube. If the sensed temperature is below thedesired setpoint, the output will be re-enabled at a variable duty cycleso that the tube is heated to the setpoint goal temperature as quicklyas possible without exceeding a maximum allowable overshoot temperature.

Normal operation consists of maintaining the fluid temperature at thedesired setpoint temperature by varying the duty cycle at which voltageis applied across the tube. The output duty cycle changes based on howfar the sensed temperature is below the set point temperature.

In the event of excessive current flow through the output, the outputwill automatically be disabled. In this event the signal at the output146 from the comparator 140 (FIG. 4) will go low. When this occurs thecontroller 14 a disables the output to the transistor for a period oftime equal to an output retry rate programmed into the controller 14 a.If the fault condition is removed, normal operation of the temperatureset point control is re-instituted. An alternate embodiment could havethe current sense capability implemented by the comparator 140 omitted.

In the event the operating voltage from the battery (and ignition) istoo high or too low (≧16.5 and ≦8 volts respectively) the controller 14a disables the output for a timeout period. After the timeout period, ifvoltage conditions are within normal parameters, the controller againenables the output. The exemplary system also incorporates a softturn-on and turn-off of the heating element. The soft turn-on andturn-off is accomplished by a slow ramp up or down of the PWM signalfrom the microprocessor 14 a that drives the heating element. Theramping of power reduces the amount of flickering that can be observedfrom the vehicle headlights. It is recognized that the FET drivers couldbe run linearly (instead of pulse width modulated) to accomplish thesoft turn-on and turn-off of the heating element. It is also recognizedthat the FET drivers could be run linearly to regulate the temperatureof the heating element. It is further recognized that if the FET driversare run linearly they will produce quantities of heat that will aid inthe heating of fluid in the system.

Turning to FIGS. 9-11, the embodiment includes a tube 322 that extendsfrom the inlet port 312 through a length of the reservoir 310 to routeunheated cleaning fluid, for example cold water, to the bottom of thereservoir. As the cleaning fluid heats inside the reservoir it tends torise. The cleaning fluid in the reservoir exits an exit port 324 at thetop of the reservoir passes through a tube 325 along an outer surface ofthe reservoir and then spirals up through the coiled outer heater tube326 to an exit port 328 (See FIG. 11).

As also depicted in FIG. 9 a plastic housing 350 of the presentlypreferred embodiment has a stepped bottom portion 352 that has an openchamber 354 sized to allow the boot 320 to expand outwardly into thechamber. The housing 350 is a molded plastic and includes inner andouter walls 360, 362 that define an air gap 366 between the walls.During construction of the assembly 10, a potting compound is added tothe housing interior and fills the region between coils of the heatingtube 326. The potting compound does not fill the air gap, however andthis air gap tends to insulate the tube and reservoir.

Alternative Embodiments

Additional features of the invention adapted for use with a motorvehicle can be realized as described below. These embodiments have thesame electrical configuration and operate in the same manner as thepreferred embodiment.

One alternative embodiment of the invention uses a communicationsinterface to transmit ambient temperature, battery voltage, washerswitch activation status, washer pump use, engine running information,and other such information to the controller. Likewise, the controllercould transmit task commands to the vehicle such as start wipers, pumpwasher fluid, controller status, and the like.

An alternate embodiment could include electronic input and/or outputcircuitry to interface with at least one ambient air temperature sensor19 that provides output signals related to a sensed state of ambient airtemperature.

Another embodiment of the invention could use engine coolant to heat thewasher fluid prior to flowing through the heating element. This willreduce the amount of power required to heat the fluid to predeterminedtemperature using the heating element.

In the embodiment illustrated by FIGS. 6, 8, and 9, the control circuitis disposed on a circuit board 160 positioned adjacent to the heatingelement 101, promoting heat transfer between the control circuit 14 andthe heating element 101. A thermal fuse 162 on the printed circuit board160 is in close proximity to the heating element. In the event that theheating element temperature surpassed a predetermined threshold, thefuse would open and disable the output drive. The control circuit 14illustrated in FIGS. 6 and 8 includes one or more heat dissipatingdevices 164 mounted to the printed circuit board. In one embodiment, aheat dissipating device 164 of the control circuit is mounted to aheating element to provide additional heating of the fluid. One suchheat dissipating device is a FET that drives the heating element. In theembodiment illustrated by FIG. 6 a heat dissipating device 164 ismounted to the reservoir 103. A heat dissipating device 164 could alsobe is mounted to a coil of one of the heating elements 30, 31, 101, 309.

Another embodiment of the invention could use a time varying signal fromthe vehicle alternator to determine if the engine is running. This couldbe used in conjunction with the ignition input or as a stand-alonesignal eliminating ignition input.

Another embodiment of the invention could use the washer pump 45 a toregulate the temperature of the washer fluid. In this embodiment thesystem would control the washer pump 45 a as well as the heatingelement. When the controller receives a request for washer use, theoutput driver would activate, heating the fluid with the heatingelement. When the washer fluid was at temperature the washer pump wouldbe enabled. After the volume of heated fluid was used the pump would bedisabled, and the fluid would again start heating to a predeterminedlevel. After the fluid achieves the desired temperature level the pumpwould again be activated.

In one embodiment, the control circuit 14 includes an output 172 thatcontrols the washer pump and separate output 174 that controls the wipermotor. This allows the control circuit to disable the wiper motor for apredetermined period of time after energizing the heating element and/orapplying the heated fluid. For example, the control circuit coulddisable the wiper motor during the first heat cycle afterinitialization. This would allow for the heated fluid to have a moresignificant impact on surface contamination such as frost before thewipers are activated.

Another embodiment would have separate user input devices 178 a, 178 bfor independent control of the washer pump and the wiper motorrespectively. The user could then spray heated fluid on the windshieldas required for cleaning independent of wiper action which tends toforce heated fluid from the windshield and thins the remaining liquidfilm causing more rapid cooling of the liquid that is left on thewindshield.

Another embodiment would have an auxiliary heating element on the innercopper reservoir 103. This would allow for more direct heating of thefluid contained in the reservoir as compared to the conduction heatingof the fluid by the outer coil through the encapsulant material. Thiswould also allow for the outer coil to be disabled when the system hasbeen in a mode of operation that only sustains the temperature of thefluid. This would allow for a lower power heat source to be enabled overlonger periods of time, compared to the high power very short durationpulses that are applied to the main heater coil. Decreasing the highcurrent requirements would decrease the wear on the vehicle's electricalsystem. It is further realized that auxiliary heating could come fromthe FET transistors that drive the heating element. It is furtherrealized that the auxiliary heating could come from a patterned heatersuch as a thermofoil heater or electro-thermal conductive flexiblegraphite, also known as vermiform graphite, such as those available fromMinco Products, Inc., 7300 Commerce Lane, Minneapolis, Minn. 55432-3177U.S.A. or EGC Enterprises Inc., 140 Parker Court, Chardon, Ohio 44024.

Similarly, another embodiment would have an auxiliary heating element183 (FIG. 8) in the inner reservoir. This would allow for more directheating of the fluid contained in the reservoir as compared to theconduction heating of the fluid by the outer coil through theencapsulant material. This would also allow the outer coil to bedisabled when the system has been in a mode of operation that onlysustains the temperature of the fluid. This would allow a lower powerheat source to be enabled over longer periods, compared to the highpower, very short duration pulses that are applied to the main heatercoil. Reducing the high current requirements would decrease the wear onthe vehicle's electrical system.

Another embodiment would have two different heat modes, the first havinga higher power, the second a lower power. The two modes of operationcould be used based on ambient temperature conditions. If, for example,it is below 40 degrees Fahrenheit where frost could be present on avehicle windshield, the unit would use high power mode to heat fluidquickly to aid the operator in its removal. Alternately, if ambienttemperature were say 40 degrees Fahrenheit or greater, a lower powermode would be used. This would allow for heating of fluid to aid in thecleaning of the windshield, but at a slower heating rate. This woulddecrease wear on the vehicle's electrical system when fast heating timesare not required. The lower power is achieved by having a lower dutycycle on the heater drive. It is understood that the decision to switchfrom a power level to another power level could be accomplished with anexternal jumper or switch. This would provide the user with means forcontrolling the power applied to the heater. It is also understood thatthe external switch or jumper could cause the selection of otherfunctions or characteristics.

Another embodiment could have a multiplicity of reservoir tanksconnected in series or parallel combination. This would give increasedavailable volume of heated fluid. Alternately, instead of havingmultiple reservoir tanks connected in one unit, multiple units could beconnected together forming a system. Another alternate configurationwould be the invention in conjunction with windshields that haveself-heating capabilities, such as those with a translucent oxidecoating enabling electrical current to flow from one end of the glass tothe other creating heat due to the resistance of the coating.

Another embodiment could use a flow switch 200 (FIG. 7) to determinewhen to heat the fluid. The control would activate the output driverwhen flow is detected so that the fluid is heated only when there is ademand. It is understood that the flow switch could be a magnet and reedswitch combination, or a magnet and a Hall Effect sensor, or a paddlewheel type, and the like.

An alternative embodiment could use two fluid temperature sensors, oneat the heater element inlet and the other at the heater element outlet.When the heater is in operation and fluid is flowing, there should be atemperature differential across the heater element. That is, a fluid ofa given temperature goes into the heater element, and warmed fluid exitsthe heater element. If the control used the washer motor voltage as aninput to initiate a heating cycle, the two fluid temperature sensorscould be used to determine that fluid flow exists. If there is atemperature differential, there would be flow. If there were a minimalor negligible temperature differential, a zero or low flow conditionwould be indicated. In the event of a low or zero flow condition, theheating element would be de-energized.

Another embodiment could have a diagnostic output that could be used forevaluating system performance and for diagnosing system faults.Operational parameters will be sent via communications such as serialcommunications using a proprietary bus or other standard bus protocol. Acomputer could be connected to the module using an appropriate interfacecable to allow for reading and interpreting data. In addition to readingdata for diagnostics, the invention could include communications andinterface means to allow for programming of the microcontroller afterthe assembly of the device is complete. This would allow for softwareupgrades on units that have finished the manufacturing process.

Another embodiment could include control of the windshield wiper motorand washer pump. A separate switch input 43 (FIGS. 1 and 1 a) wouldactivate a cycle to dispense the fluid.

Another embodiment could include control of the windshield wiper motorand washer pump. A switch input would activate an automatic cycle todispense the fluid.

Another embodiment could include control of the windshield wiper motorand washer pump. A signal could be sent to an existing control module toinitiate a washer and/or wiper sequence of operation as shown in FIG.45. It is also understood that the heated washer module functionalityand the vehicle washer/wiper control module could he combined to form asingle integrated module illustrated in FIG. 46.

In another embodiment, the module would control delayed wiper functionsand would also have a switch input for one-touch control of the wipermotor and washer pump for spraying of washer fluid in an automatic washcycle with an automatic wash cycle consisting of a given number ofwasher pump cycles and given number of wiper motor excursions. It isunderstood that cycle counts and motor excursions could be substitutedfor given times.

FIG. 16 is a schematic depiction of a vehicle system with a generallylong fluid path to the spray nozzle locations. Between cycles of useractivation, the time heated fluid remains in the fluid line 392 betweenthe outlet 34 of washer control system 10 and spray nozzle(s) 37 cancause the resident fluid to cool. One embodiment of a vehicle washersystem using a fluid re-circulation method is shown. “Y” or “T” fitting393 is connected to fluid line 392 between outlet 34 and nozzle(s) 37.If the heated fluid remains in fluid line 392 a predetermined timebetween cycles of user activation, control circuit 14 of FIG. 8 wouldactivate a second pump 395 to redirect the fluid through hoseconnections 394, 396 back to inlet 32 of washer control system 10 bymeans of “Y” or “T” fitting 397 into hose connection 399. Re-circulatedfluid could alternatively be dispensed back into fluid bottle 391 ifdesired. Pressure sensitive check valve 398 would be used to effectivelystop fluid flow ahead of nozzle(s) 37 and limit the dispensing ofunwanted cool fluid to a small amount. An alternate method of providingheated fluid is to allow the fluid in the distribution tube to bleedback into the heated reservoir. Referring to FIG. 23, in the event thatthe vehicle has been off for an amount of time that allows the fluid inthe distribution tube to cool to ambient temperature, a method isdesirable to have only heated fluid spray on the windshield and not thecooled fluid. Bleed hole 450 in heater coil 355 allows fluid from thenozzles to the heater to drain back into chamber 383. Upon reactivationof system with vehicle start the fluid in chamber 383 and heater coil355 will be heated to a desired temperature. When fluid use is desiredfluid will be pumped into the distribution tube and dispensed throughnozzles 37.

FIGS. 17 and 18 depict an alternate embodiment of a washer controlsystem 10 to address concerns about excessive fluid pressure drop causedby flow through a continuous heater coil. FIG. 18 depicts a heater coilconfiguration using two coils of the same diameter and wall thickness,joined together by a single adapter used to route fluid to an outlet410. The heater coil material could be annealed 304 series stainlesssteel, or other materials high in electrical resistivity. As fluid isdispensed through first port 406, it fills housing reservoir 401. Thefirst coil 402 receives the fluid through first inlet 405. At the sametime, second coil 404 receives fluid through second inlet 407, as shownin FIG. 19. First coil 402 is connected to second coil 404 by means ofadapter 403, best shown in FIG. 20. The preferred adapter 403 materialis copper, made from a powdered metal process. FIG. 20 also showsintegrating thermistor 408 and thermal fuse 409 into adapter 403, formeasuring coil temperatures as a functional part of control circuit 14.The heated fluid then exits through second port 410 and is routed to thedispense nozzles onto the vehicle windshield, headlamps, etc. Thecombined fluid flow through each of the first inlet 405 and the secondinlet 407 is half that of a continuous length of coil equaling thecombined length of the two coils 402 and 404, with a resultant pressuredrop equal to one quarter of a continuous coil. FIG. 22 is a schematicrepresentation of the apparatus described in FIGS. 17-20. Afterreservoir 407 receives fluid through inlet 406, the schematic shows thedual path for the fluid flow through inlets 405 and 407 to outlet 410.Terminals 421 and 422 represent power connections to provide continuouscurrent flow path for the entire length of combined heater coils 402 and404.

FIG. 21 is a front view of another embodiment where a heating element isintegrated with a fluid bottle on a motor vehicle, and where the fluidsupply line serves as the heating element. The configuration depicts across-sectioned area of dual chambered fluid bottle 411, which is filledthrough filler neck 412 allowing fluid to enter into first chamber 415.Pump 378, exteriorly mounted to an outer wall of chamber 415, drawsfluid from chamber 415 through hose connection 416, and dispenses intosecond chamber 414 through port 418. Pump 378 is generally located forcapability of drawing fluid from the bottom level of bottle 411 forpumping fluid to a near empty condition. As chamber 414 is pressurized,fluid is forced into an inlet 419 of continuous length heater tube 413.A first segment 417 of continuous length heater tube 413 is positionedinside walled chamber 414, and includes an opening or openings 420 atthe highest elevation of the segment to allow an escape of trapped airas fluid fills the chamber 414. The heater tube 413 exits chamber 414through a grommet seal 425 and includes electrical terminal connections421 and 422 on each end. The segment of heater tube 413 exterior tofluid bottle 411 is the active heater element of washer control system10. Heater tube 413 extends continuously through control circuit 14.Conductor wire 423 connects to terminal 421, and terminates toelectrical battery connection 51 inside control circuit 14. Conductorwire 426 connects to terminal 422, and terminates to ground connection52 inside control circuit 14. As power is applied, the fluid insideheater tube 413 is rapidly heated before exiting through flexible tube427 and routed to the dispense nozzles 37 onto the vehicle windshield,headlamps, etc. Pressure sensitive check valve 428 could be used toeffectively stop fluid flow between heater tube 413 and nozzles 37 atthe conclusion of user activation and limit the dispensing of unwantedcool fluid to a small amount during the next user command. Heater tube413 and conductor wires 423, 426 could be routed parallel to each other,and insulated commonly with a sleeve 424, which has thermal insulatingproperties to prevent heat loss. Sleeve 424 could also provide forenvironmental sealing of terminal connections 421, 422. The largerunheated volume of fluid is contained in the first chamber 415 of thefluid bottle 411, and double walled chamber 414 acts as a reserve foradditional fluid, conductively heated by the first segment 417 ofcontinuous length heater tube 413. The double wall 429 is separated byone or more air cavity features 430, providing insulation between thecolder fluid contained in first chamber 415 and the conductively heatedfluid contained in the second chamber 414, thereby conserving heat lossand energy.

Further Alternative Embodiments

Referring to FIG. 23, a washer control system 10 in accordance withanother embodiment is shown in cross-section. This embodiment includesfeatures as described in FIG. 22 for reducing pressure drop, as well ascompensation for freeze expansion as previously described in FIG. 9 andother embodiments. FIG. 25 represents a projected top view of FIG. 23.

A heater element is comprised of first and second heater coils 500 and501, which are brazed or otherwise attached to a reservoir 502. Aninsulator 503 surrounding the reservoir electrically isolates the coils500, 501 from the reservoir 502. The reservoir 502 is enclosed on oneend by cap 504, and on the other by freeze expansion elastic 505, whichseals against the open end of a housing 506. The freeze expansionelastomer 505 is protected from damage by a protective cup 507, which issecured against the open end of housing 506. This provides a sealedchamber 508 to allow freeze expansion. A PCB 509 is electricallyconnected to the heater coils 500 and 501 by means of terminals 510 and511, which are brazed onto the coils 500 and 501. Rivet fasteners 512and 513 make a mechanical attachment between the terminals and the PCB.

A power FET component 514 is also attached to the PCB by means of therivet 512. Battery positive and ground are applied to washer controlsystem 10 through terminals 515 and 516, as shown in FIG. 25. Ignitionsource is provided through terminal 517. All terminals are electricallyconnected to the PCB 509. Mating connections are made through connector518. The heater coils 500 and 501 exit fluid into a fluid coupler 519,where it is dispensed through outlet feature 520 in cover 521. Fluidhose 522 carries heated fluid to the vehicle windshield, headlamps, etc.The exit ends of the heater coils 500 and 501 are sealed into the fluidcoupler 519 by means of o-rings. Likewise, the fluid coupler 519 sealsinto the cover 521 with an o-ring. The washer control system 10 issealed using potting compound 523.

Another embodiment shown in FIG. 24 has a primary heating wire 465submerged in the fluid. This allows for direct heating of the fluidcontained in the reservoir 462 as compared to the conduction heating ofthe fluid by the outer coil through the encapsulant material. The fluidin a reservoir 462 exits an exit port 463 at the bottom of the reservoirand passes into a fluid chamber 464 along an outer surface of thereservoir. The fluid then comes in contact with the heater wire 465,where it is heated before exiting through an exit port 466. In thedescribed embodiment, the heater wire has an uncoiled length of 6 to 7feet and is constructed of 10 gage stainless steel solid wire. Whencoiled to the configuration shown in FIG. 24, the coiled heating elementhas an inside diameter of 1½ inches. A tube 461 extends from the inletport 460 through a length of the reservoir 462 to route cold fluid tothe bottom of the reservoir because as the fluid heats inside thereservoir it tends to rise.

Fluid chamber 464 holds a relatively small volume of fluid to minimizethe heating time and allow heat from the heated fluid to then conductthrough the wall of reservoir 462 and provide secondary heating of thefluid contained therein. The reservoir 462 is constructed from a plasticmaterial, preferably containing glass fiber reinforcement for betterconduction of heat. One suitable reservoir is constructed from glassreinforced High Density Polyethylene (HDPE). Another preferredconstruction of the reservoir 462 is to include a spiral feature thatmates with heater wire 465 and functions to prohibit unintentionalelectrical shorting of adjacent coils.

As also depicted in FIG. 24, a plastic housing 467 of the embodiment hasa stepped bottom portion 468 that has an open chamber 469 sized to allowthe elastic member 470 to expand outwardly into the chamber duringfreeze conditions. The housing 467 is a molded plastic and includesinner and outer walls 471, 472 that define an air gap 473 between thewalls. The air gap functions as an insulator for the heated fluid insidethe fluid chamber 464 and the reservoir 462. One suitable housing isconstructed from glass reinforced High Density Polyethylene (HDPE).

FIGS. 33 a and 33 b illustrate an embodiment of a washer control system10 that is different from that described previously due to thereplacement of control circuit 14 with a thermal fuse device 524 and abi-metal device 525. FIG. 33 a is a schematic depiction of such acontrol circuit. The thermal fuse 524 prevents the washer control system10 from overheating, while the bi-metal device 525 regulates heatingduring operation. The bi-metal device could control a relay 612 (seecontrol circuit schematic 33 b) that supplies power to the heatingelement. In addition, at least one temperature sensor could be used inconjunction with a reference to control a relay that supplies power tothe heating element.

FIGS. 28 and 29 illustrate a washer control system 10 that includes aheater element 30 that is comprised of first and second heater coils 530and 531 positioned closely around a reservoir 534. The reservoir 534 ismade from a plastic material with a combination of stiffness andflexibility, such as high density polyethylene (HDPE) blended withthermoplastic rubber. The Kuraray Group makes a formulation of 85% HDPEblended with 15% HYBRAR® 5127 thermoplastic rubber. An alternativematerial could be a polypropylene (PP) such as Marlex® HHX-007 fromPhillips Sumika Polypropylene Company). The reservoir 534 is enclosed onone end and open on the other end until joined with reservoir end cap533, which forms a liquid tight seal by means of inner o-ring 535, andouter o-ring 537. An outer band portion 539 of the end cap 533 providessupport for the open end portion of the reservoir 534 against plasticcreep from sealing forces exerted by the inner o-ring 535. The outero-ring 537 provides redundant sealing to prevent fluid leakage duringhigh pressure operation of the washer control system 10. The end cap 533is made from copper alloy for electrical and thermal conductivityproperties, employing powder metallurgy processing techniques in thepreferred embodiment. The end cap 533 could also be made from othermaterials with good thermal conductivity properties, such as brass oraluminum, and could be manufactured using other methods such as diecasting.

The reservoir 534 could have both ends open, using another metal end capsimilar to that described for end cap 533 to make a fluid container. Apower FET component 541 is soldered to the PCB 536 and then attached tothe end cap 533 by means of fastener 555. The end cap 533 is constructedwith a plurality of heat-sink projections 540 which project into thefluid chamber of the reservoir 534, allowing the power FET 541 todissipate heat during operation. In the preferred embodiment, theheat-sink protrusions 540 are generally round in shape, but could be anyshape that provides adequate surface area for heat-sinking performance,such as heat-sink protrusions 540′ shown in FIG. 38.

The washer fluid contained inside the reservoir 534 acts to cool theheat-sink contact surface by means of thermal conduction through thecopper material of end cap 533. Conversely, the dissipating heat fromthe power FET 541 thermally conducts heat into the washer fluidcontained in reservoir 534 to provide added heat for cleaning, therebyincreasing performance efficiency. An adapter 532, preferably also madefrom powdered metal copper alloy, can be fastened to the end cap 533 byany means well known in the art to provide a liquid tight seal with goodelectrical connection, including brazing, soldering or welding. Thepreferred method of fastening is by means of bonding into a one-piecepart with the end cap 533 during sintering in the powdered metalprocess.

Referring to FIG. 29, the coil 530 can be fastened to reservoir adapter532 by any means well known in the art to provide a liquid tight sealwith good electrical connection, including brazing, soldering orwelding. The preferred method of fastening is by means of flaring thetube end and connecting with compression fitting to the adapter 532.Coils 530 and 531 are electrically connected to each other by means ofbus bar 545, which is made from a spring brass or copper material forcurrent carrying capability. The bus bar 545 has two holes with die cutspring features for providing a press or interference fit when the coils530 and 531 pass through the holes in assembly, eliminating the need tomechanically and electrically attach parts with soldering, brazing orwelding methods. The PCB 536 is electrically connected to the heatercoil 531 by means of an adapter 532, which extends to be in contact witha printed copper conductor on PCB 536 and is secured in place with afastener. Likewise, the heater coil 530 electrically connects to the PCB536 by means of an adapter 529, which extends to be in contact with aprinted copper conductor on the PCB 536 and is secured in place with afastener (not shown).

Referring to FIG. 32, terminals 562 and 546 are tin plated brassconductors for carrying high current from the vehicle battery to the PCB536. In the preferred embodiment, these terminals are 0.250 inch wideand 0.032 inch thick, and are constructed with features intended tosecure them into the connector shell 547 using methods well known in theart. Tab portions of terminals 562 and 546 pass through the openings inPCB 536 and are soldered to make the electrical connection of the coils530 and 531. In the preferred embodiment, the tab portion is crimpedonce it passes through the PCB 536 in order to provide a mechanicalconnection during solder processing.

A connector shell 547, which is preferably made from 30% glassreinforced polybutylene-terephthalate (polyester PBT), such as G.E.Plastics Valox® 420, also accepts terminals 549, 550, 551, 552 and 553,which also pass through openings in the PCB 536 and are soldered inplace to carry electrical signal commands to and from a control circuitsuch as the control circuit 14 (FIG. 1). The terminals 549, 550, 551,552 and 553 are preferably made from tin plated brass. The connectorshell 547 secures into housing 548 by means of matching tongue andgroove features in each part, and seals (not shown). The housing 548 ispreferably made from 30% glass reinforced polybutylene-terephthalate(polyester PBT), such as G.E. Plastics Valox® 420, and accepts heaterassembly 556. A plurality of ribs 557 extend from the walls of thehousing 548 and function to locate the coils 530 and 531, keeping themelectrically isolated. In addition, ribs 557 provide support for theheater assembly 556. The PCB is supported on alignment bosses 597 (FIG.30) molded into the housing 548. The PCB 536 is sealed against the shelfwith silicone or other such types of adhesive gasket forming materials.A cover 560 is preferably made from 15% glass reinforced PBT such asG.E. Plastics Valox® DR51.

Another source of heating for the fluid contained in the reservoir 534is by means of heat radiated off the heated coils 530 and 531. The heatcontained within the housing 548 thereby acts to warm the fluidcontained in the reservoir 534, again increasing performance efficiency.Heat radiation can be enhanced by means of providing a reflectivesurface on the inside of housing 548. Black and other colored plasticswould absorb heat, causing radiated heat from coils 530 and 531 todissipate away from reservoir 534. A reflective surface, such as onethat may be applied by means of vacuum deposition for instance,selectively plated to the walls of the housing 548 adjacent to the coils530 and 531, would assist in keeping the radiated heat contained.

Battery positive and ground are applied to washer control system 10through terminals 562 and 546, as shown in FIG. 32. Ignition source isprovided through terminal 549. The heater coils 530 and 531 exit fluidinto a fluid coupler 561, as shown in FIG. 44, where it is dispensedthrough an outlet feature 563 in a cover 560. A fluid hose (FIGS. 16 and21) carries heated fluid to the vehicle windshield, headlamps, etc. Theexit ends of heater coils 530 and 531 are sealed into the fluid coupler561 by means of a seal 567. Fluid coupler 561 is integral to cover 560.The washer control system 10 can be sealed using potting compound suchas is shown in FIG. 23, reference character 523.

Referring to FIG. 31, a cross-section view from the end of washercontrol system 10 shows reservoir 534 is shaped with inwardly contouredspring features 541, 542, 543 and 544. During conditions where the fluidis allowed to freeze inside reservoir 534, the spring features 541, 542,543 and 544 can expand outward to accommodate the volume of the frozenfluid. The flexible properties of plastic reservoir 534 is such to allowexpansion for preventing damage that would cause fluid leakage, andcontraction for return to its pre-expanded shape. A further function ofthe contoured spring features of reservoir 534 is their strength towithstand normal operation fluid pressure, which could be as high as 50psi. It is important that reservoir 534 maintain its non-expanded shapeduring operation in order to avoid extra fluid exiting the vehicle spraynozzles following a wash command by the user. If operating pressurecauses reservoir 534 to expand, unwanted extra fluid can be dispensedwhen pressure is relieved following a user ending a wash command.Pressures higher than 50 psi, such as those caused by the expansion offreezing fluid, allow spring features 541, 542, 543 and 544 to moveoutwardly.

FIGS. 34-38 illustrate an alternative embodiment of the inventive washersystem. Referring to FIG. 34, the heater 30 is energized with batteryvoltage by a relay 632 that is activated by ignition of the vehicle. Athermal fuse 637 is in series with the relay coil and is in proximity tothe heater coil 30. If the heater coil becomes too hot, the thermal fusewill open and voltage is removed from the heater. The control circuit 14shown in FIG. 1 provides a digital signal to a heater energizationcircuit 630 shown in FIG. 34. The digital signal 635 from the controlleris converted to an analog voltage by a converter circuit 638. Theconverted voltage is provided to a FET 645 as a gate voltage. The gatevoltage varies between zero to a FET saturation voltage. The FET 645 ispart of a current path for the heater 30 and dissipates an amount ofheat that is proportional to the driving voltage that is supplied to it.Since battery voltage is monitored, and the resistance of the heatercoil is known, current flowing through the heater can be calculated bythe control circuit 14 to set and regulate the gate voltage. Bycontrolling the relative amounts of power dissipated in the FET andheater coils, the control circuit can apply varying amounts of heat fromeach of the two heat sources to maintain a desired fluid temperature.

FIG. 35 is a perspective view of washer control system that includes theheater energization circuit described in conjunction with FIG. 34. Areservoir 653 is surrounded by heater coils 500, 501. Fluid enters thereservoir through inlet 642. Fluid flows from the reservoir 653 to theheater coil 500 through an end cap 650. Fluid exits the nozzles throughan adapter 647 that has an outlet for each heater coil. The FET 645 ismounted on a dedicated board held in place with a clip on the end cap650. The thermal communication between the FET 645 and the end cap 650allows heat to be conducted from the FET through the end cap into thereservoir 653 to heat the fluid in the reservoir prior to its entry intothe heater coils. FIGS. 36 and 37 show the washer control system with acircuit board 667 that houses the control circuit 14. The heater coil501 can be seen as it is connected to the reservoir 653.

Referring to FIG. 39, a section view of control system 10 shows heatercoils 530 and 531 covered with an elastic material 670. Duringconditions where fluid is allowed to freeze inside the heater coils, itis well known that the metal tubing from which they are constructed willexpand. After repeated freeze and thaw cycles, the metal can expand tothe point where it yields completely, causing thawed fluid to leak outof the control system 10. In the preferred embodiment, the fluidcontaining heater coils 530 and 531 are enclosed within elastic material670, which can be any material such as urethane tubing, nylon tubing orthe like, covering the majority of the surface areas of heater coils 530and 531 to contain fluid within the heating element, ensuring thatcontrol system functionality is maintained even if the metal heatingcoils burst.

The heater coils 530 and 531 could also have a multiplicity of notchesintroduced to the heater element surfaces to serve as stressconcentration points for the purpose of directing the describedexpansion yield point to a specific location or locations. These notchescould be very shallow details, approximately 0.005 inch in depth and0.25 inches in length, located approximately 3 inches apart or the like.The sectional shape could be in the form of a “V” to accentuate thestress concentration. The introduction of such notches would serve toforce ruptures to occur in a controlled location.

In a preferred embodiment, elastic material 670 is non-electricallyconductive. Those properties provide a further function of elasticmaterial 670 to electrically insulate heater coils 530 and 531 toprevent electrical shorting.

FIGS. 40, 41, and 42 depict an alternate embodiment of control system10. FIGS. 41 and 42 show the system with a cover component 676 removed.In this embodiment, control system 10 receives fluid through an inletport 681 that then enters into a heatsink 674. A previously describedpower FET component 514 is electrically and mechanically attached toprinted circuit board (PCB) 675, using well known methods, and is joinedwith heatsink 674 by means of a threaded fastener or the like. Theheatsink 674 is preferably made from copper, or alloy materials such asaluminum that are similarly effective in thermal transfer. The heatsink674 is configured such to contain a small volume of fluid, preferablysituated directly opposite the flat mounting surface of power FET 514,ideally for the purpose of cooling power FET 514 during systemoperation. Conversely, heat transferring from power FET 514 through theheatsink 674 serves to heat the fluid in the reservoir area, adding tothe performance of control system 10. Heatsink 674 also provideselectrical connection between the PCB 675 and the first heater coil 671.Fluid passes from heatsink 674 into first heater coil 671 throughaperture 677, through temperature sensor fitting 678 and into secondheater coil 672. Fluid dispenses into check valve block 680 through anentryway 679 and exits control system 10 by means of outlet port 673.Check valve block 680 also provides electrical connection between PCB675 and second heater coil 672, and is preferably made from copper, orany alloy material capable of withstanding long term exposure to typicalfluids used in vehicle washer systems. The assembly as described ispreferably attached to base component 682 and enclosed in the cover 676,which are preferably molded from plastic material such as 30% glassreinforced polyester, such as that made by GE Plastics under the tradename Valox®. There are many other suitable materials available capableof withstanding the environment and conditions typical of those under avehicle engine compartment. Power is supplied to this embodiment ofcontrol system 10 by means of a connector assembly 683, while input andoutput commands are administered by means of a connector assembly 684.

Referring now to FIG. 43, a section view is shown of heater coil 672within control system 10. A portion of washer fluid is allowed to passthrough heating element 685, while another portion flows outside and iscontained within loosely fit outer tube 686. Fluid enters both tubesgenerally simultaneously through the outlet 677 of heatsink 674 and bothportions exit generally together through the inlet 679 to check valveblock 680. Fluid is heated by being in direct contact with both theinside and outside diameters of heating element 685 along its entirelength. The same inner and outer tubing arrangement described here ispresent in heater coil 671, which is not shown in FIG. 43.

As previously disclosed, the heating element 685 is made from anelectrically conductive metal, preferably type 304 stainless steel, butcould be any material with similar high electrical resistivityproperties capable of conducting electricity dependent on the sizerestraints of a particular control system application. Outer tube 686 ispreferably made from an electrically non-conductive material withelastic properties that is expandable during freeze conditions, therebypreventing loss of both fluid and system functionality in the event of abreak in a heating element. It is preferred that this material alsoexhibits characteristics of strength in order to maintain its generalsize and shape in withstanding typical vehicle washer system operatingpressures, which could be as high as 50 psi. One adequate material forthis purpose is nylon 12.

This embodiment of the heater coil also ensures that a desired systemfluid flow can be maintained. System size restraints often dictate thenecessary tubing size required for given performance, and thoserestraints in some embodiments can result in undesirable fluid pressuredrop at the nozzles where the fluid is dispensed onto a surface aspreviously described. In the embodiment as shown in FIGS. 40-43, alonger length of heating element 685 can be configured with a smallerinside diameter in an effort to reduce the overall size of controlsystem 10. The resulting pressure drop along the length of the heatingelement caused by restricting the fluid flow through the small insidediameter of heating element 685 may not meet acceptable performancerequirements for the system. However, if the heating element 685 andouter tube 686 are collectively used to convey heated fluid, sufficientflow to a vehicle windshield surface or the like is provided if thepassageways are properly sized.

A further embodiment allows for the determination of alcohol content ofthe washer fluid. If the alcohol to water ratio is know with some levelof particularity, it is possible to alter the temperature thresholdaccordingly to achieve higher temperatures if there is a higherconcentration of water. It is well known that alcohols used in washerfluid will boil at a temperature lower than that of water. Typically,the boiling points of said alcohols are around 150° F. while water is at212° F. Raising the temperature threshold based on alcohol content mayallow for improved efficiency in the removal of frost/ice and proteindeposits. A further function of knowing the concentration of alcohol inthe washer fluid is to provide a warning to the operator in the event ofinadequate alcohol so that damage to the system will not occur due tofreezing.

Referring to FIG. 44, a section view of control system 10 shows probe696 mounted in the lid 560 of control system 10. The probes protrudethrough a wall section of the lid and into communication with fluidcontained within the fluid coupler 561. Signals of some particularityare then placed on probe 696 for the purpose of providing signals tocircuitry located on a printed circuit board that can be used todetermine an approximation of the dielectric constant of the fluid. Thedielectric constant of isopropyl alcohol is approximately 18 at 68° F.and that of water is 1 at 68° F. It can be seen that the ratio of waterto alcohol can be derived by using the dielectric constant of the fluid.This method can be used to determine the alcohol content of the washerfluid. Additional details of alcohol sensing are found in issued U.S.Pat. No. 7,055,505 B2 which is incorporated herein by reference.

A further embodiment the heater assembly is integrated into a wipermotor system. Referencing FIG. 47 the system 700 contains the elementsof heater assembly 10 and wiper control electronics typically found inan automotive environment. The system further consists of a motor,linkages, gears, wiper arms and the like of a typical automotive wipersystem. Integrated control 710 is mounted to the wiper arm assemblyforming a wiper motor and heated washer system. Fluid flow going tospray nozzles may be remote from the heated washer system or the spraynozzles may be integral with the windshield wiper arm portion of thewiper arm assembly. It is understood that the electronic control couldalso be mounted integral to the motor housing. The control accepts inputto energize the wiper motor either continuously or on an intermittent ordelayed basis. The control also accepts input to instigate the heatingfunctions. It is understood that the control electronics could bepackaged remotely from the wiper assembly. It is further understood thatthe control electronics with the heater function could be locatedremotely from the wiper assembly.

A further embodiment of the heater and wiper motor assembly referencedin FIG. 47 is to integrate the washer pump function into the assembly.Washer pumps are typically found in or in proximity to the washer fluidreservoir which may or may not be in proximity to the wiper motor. Atypical washer pump consists of components typical of a dc motor drivenpump such as an armature, a motor shaft, an impeller, brushes, etc. Theembodiment shown in FIG. 48 has integrated the washer pump function intothe wiper motor assembly to provide a common assembly 800 for drivingthe windshield wipers 802, 804.

FIG. 49 shows pump components and the wiper motor components that makeup a part of assembly 800. An electric motor 820 drives a worm gear 830that is connected to a motor output shaft. The worm gear 830 in turnrotates a drive gear 840 that is connected to a wiper arm mechanism 842.Wiper arm mechanism 842 connects to wiper arm drive linkage 855 using abearing pin or shaft through hole 856. Worm and worm gear design is awell known art and design guidelines can be found in various sourcessuch as on Page 1876 of the Machinery's Handbook, 23^(rd) edition, Thirdprinting 1990, printed by Industrial Press Inc., 200 Madison Ave., NewYork N.Y. 10015-4078. Conversion of rotational motion of the mechanism842 into back and forth motion of a wiper blade is a well known and canbe accomplished in a number of ways.

Typically the motor shaft and worm gear are rotating at a rateapproximately 50 times faster than the drive gear 840. This higher speedon the motor shaft can be used to drive an impeller 810 located in apump housing 812 (FIG. 50) that will pump washer fluid whenever thewiper motor is active. The impeller could be activated by use of aclutch mechanism 815 (FIG. 50) that will connect the impeller 810 to thedrive shaft of the motor 820. The clutch mechanism 815 is electricallyactivated whenever the washer button or switch 113 in the vehicle ispressed or when the washer heater control 14 requests washer activation.Alternately a fluid driven clutch mechanism could be used.

In the event washer arm 806 is not able to move due to mechanical issuesor the blade being frozen to the windshield, the washer pump isprevented from dispensing fluid. If fluid was allowed to be dispensed itcould adversely effect the driver's vision.

It is understood that the impeller could be mounted through a gearmechanism or flexible coupling that will change the orientation to themotor by an angle such as 90 degrees. It is further understood that if adifferent speed of rotation is needed for the impeller various standardmeans such as gear trains could be employed to achieve the desired rateof rotation. It is clear from the description that there is a costadvantage to be realized by the removal of a motor housing, an armature,a shaft, motor brushes, and other various components by using anexisting motor to accomplish fluid pumping and wiper arm movement.

As depicted in FIG. 50, the pump portion of assembly 800 would pullfluid from a washer fluid reservoir (not shown) through an inlet 822whenever the wash function is requested by the vehicle operator. Ondemand pumping of fluid would dictate that the pump would need be selfpriming or be primed and ready to dispense fluid. Typically inautomotive washer systems there are check valves in the washer system toprevent the back flow of fluid from the washer nozzles to the fluidreservoir. The check valve can be located in the fluid path located inthe reservoir 534; other systems have check valves located in the spraynozzles such as those from Daimler Chrysler Corporation. The use ofcheck valves will ensure that fluid is in the pumping chamber 545 inwhich impeller 810 resides. In the event that there is no fluid in thetubing or impeller chamber, the pump mechanism will be capable of selfpriming by using established techniques know in the arts by creating alow pressure area at the impeller chamber inlet thus causing washerfluid to be drawn into the pump.

The pump portion of the assembly could contain sensing capabilities todetermine if fluid was present in the pump chamber. If fluid was notpresent there would be less pressure at the outlet of the impellerchamber. This lower pressure could be sensed by a pressure sensor. Thepressure sensor could be electronic or mechanical in construction. Anelectronic sensor 825 could be employed such as the piezoresistivesilicon pressure sensor Model number 1451-050G-T from MeasurementSpecialties, Inc., Sensor Division and Consumer Sales, 1000 Lucas Way,Hampton Va. 23666. Alternately a mechanical construction could be aspring loaded plunger that held a magnet. With sufficient pressure themagnet would be pressed into proximity with a magnetic reed switch. Aclosed switch would result from a higher level of pressure indicatingthat there was fluid present. An open switch would result from lowerpressure and indicate the need to add fluid. An alternate sensingmechanism could be a spring load vane to sense fluid flow. Similarconfigurations using magnets and reed switches previously describedcould be used with this mechanism. A further alternate fluid sensingmethod employs dielectric sensor 696. (FIG. 44) When there is no fluidavailable the sensor will give an indication of a very low dielectricconstant approaching 1 (air). The fact that the fluid level is low orthat there is no fluid will be communicated to the vehicle operator viaan indication such as a light or and audible tone or a text messagedisplayed on an information center display.

FIG. 50 shows assembly 800 including the motor with integral washer pumpfurther integrated with a washer fluid heater forming awiper/washer/heater system. A section view is shown of heater coils 530and 531 within control system 10. A fluid inlet 822 of system 10 acceptsfluid from the washer fluid reservoir and directs it to pump chamber545. An outlet 824 of pump chamber 545 directs fluid flow into heaterreservoir 534 and heater coils 530 and 531. The heater coils 530 and 531exit fluid into a fluid coupler 561 where it is dispensed through anoutlet feature 563 in a cover 560 (FIG. 44). A fluid hose (FIGS. 16 and21) carries heated fluid to the vehicle windshield. It is understoodthat the fluid coming from the assembly 800 could route fluid to spraynozzles mounted either on the wiper arms or remote to the wiper armssuch as the hood of an automobile or on a cowling located at the base ofa windshield.

FIG. 51 shows a system similar to that described in FIG. 48 but for asingle wiper arm 806 such as what would be found on the rear window ofan SUV or a minivan. It is understood that various configuration arepossible including having the control electronics mounted remote fromthe motor and heater. It is further understood that the controlelectronics could be integrated with the motor and pump assembly and theheater coils and reservoir could be located remote from said assembly.

While the invention has been described with a degree of particularity,it is the intent that the invention includes all modifications andalterations from the disclosed design falling within the spirit or scopeof the appended claims.

1. Apparatus for providing a heated cleaning fluid to a vehicle surfacecomprising: a) an inlet port for receiving an amount of fluid; b) anoutlet port in fluid communication with the reservoir for dispensing anamount of heated fluid; c) a metal heater coil having an interiorpassageway for heating fluid that passes from the inlet to the outletport through said passageway; wherein the heater coil is covered, atleast in part by an elastic material for containing fluid in the eventof a ruptured heating element caused by one or more freeze/thawexpansion and contraction cycles; and d) a control circuit forenergizing at least a portion of the metal heating coil with a voltageto heat the heating element and the fluid passing from the inlet to theoutlet.
 2. The apparatus of claim 1 comprising: a) a fluid reservoir;and b) a plurality of heater coils covered with the elastic materialthrough which fluid can flow wherein the heater coils are in thermalcommunication with the fluid reservoir.
 3. The apparatus of claim 2wherein the fluid reservoir is plastic and includes an expandableportion or portions that expands when fluid in the reservoir freezes toprevent damage to the reservoir.
 4. The apparatus of claim 1 wherein thefluid reservoir is made of a material that flexes to expand duringfreezing.
 5. The apparatus of claim 1 comprising a pump for pumpingfluid through the heating metal heating coil.
 6. The apparatus of claim5 wherein the pump is comprised of a motor driving a single shaft. 7.The apparatus of claim 2 wherein thermal communication between theheater coils and the reservoir occurs through an encapsulant that isthermally conductive to transfer heat between the heater coils and thereservoir.
 8. The apparatus of claim 7 wherein the encapsulant also actsto retain heat to provide sustained heating of the reservoir whenelectrical energy is not being applied.
 9. The apparatus of claim 2comprising a heat dissipating device that thermally conducts heat intothe fluid contained in the reservoir to provide additional heating ofthe fluid therein.
 10. The apparatus of claim 9 wherein the heatdissipating device comprises a power FET that is supplied with avariable gate voltage by the control circuit.
 11. The apparatus of claim10 wherein the control circuit divides a total power into a percentageof applied power to each of the heater coils and power FET as a means ofcontrolling the speed of heating of each based on the demand for fastheating of fluid or heating of reserve fluid.
 12. The apparatus of claim2 wherein the two heater coils are isolated in order to preventelectrical shorting.
 13. The apparatus of claim 12 wherein the heatercoils are isolated by a plurality of plastic spacing members eitherconnected integrally with the enclosure or attached as separateconnecting parts of the heating element assembly.
 14. The apparatus ofclaim 1 comprising two heater coils, each constructed from anelectrically conductive tube connected in series and further comprisinga reservoir connected to the heater coils by means of sealed fittings.15. The apparatus of claim 14 wherein the sealed fittings are metaladapters that are coupled to the heater coil by means of flaring thetubing ends and securing in place with a threaded fastener.
 16. Theapparatus according to claim 1, wherein the heater coil has an outersurface spaced from the elastic material so that a heating fluid isrouted both inside and outside the metal wall of said heater coil. 17.The apparatus of claim 16 wherein the elastic material comprises alarger diameter tube fixed loosely over the heater coil to capture fluidflowing along an outside surface of the heater coil.
 18. The apparatusaccording to claim 17, wherein the larger diameter tube fixed looselyover the heater coil is an electrically non-conductive material withelastic properties that is expandable during freeze conditions, therebypreventing breakage and loss of fluid and system functionality.
 19. Theapparatus of claim 1 additionally comprising a probe for sensing alcoholcontent of fluid entering the inlet port.
 20. A method for providing aheated cleaning fluid to a vehicle surface comprising: a) coupling anelectrically conductive fluid carrying tube to a source of cleaningfluid; b) routing a cleaning fluid into an inlet port of the tube suchthat the fluid flows from the inlet to an outlet port of said tube; c)energizing said tube with a voltage to heat the fluid carrying tube andthe fluid passing through the tube; d) directing the fluid from theoutlet port to a nozzle for dispensing heated fluid against saidsurface; and e) covering at least a portion of the fluid carrying tubewith an elastic material to contain fluid in the event of a rupturedtube caused by one or more freeze/thaw expansion and contraction cycles.21. The method of claim 20 wherein said tube is energized with saidvoltage through a power switch FET by supplying a variable gate voltageto said FET to determine an amount of heat to be dissipated by said FETand wherein said FET is positioned proximate said tube such that saidfluid in said tube acts as a heat sink for said power switch.
 22. Themethod of claim 20 wherein about 150 ml of heated fluid is dispensedagainst said surface.
 23. The method of claim 20 wherein the elasticmaterial is a plastic tube having an inner diameter that is larger thanan outside diameter of the conductive fluid carrying tube and furtherwherein fluid is routed with a region between the inner diameter of theplastic tube and the outer diameter of the conductive fluid carryingtube. 24-30. (canceled)
 31. A method for providing a heated cleaningfluid to a vehicle surface comprising: a) covering an electricallyconductive heating element with a flexible plastic tube having anelongated length sufficient to heat fluid passing through the flexibleplastic tube; b) routing a cleaning fluid into an inlet port of theplastic tube such that the fluid flows from the inlet to an outlet portof said tube; c) energizing the heating element to heat the fluidpassing through the tube; d) directing the fluid from the outlet port ofthe tube to a nozzle for dispensing heated fluid against said surface.32. The method of claim 31 wherein the heating element is an elongatedmember having electrical contacts at either end which extends throughthe plastic tube.
 33. The method of claim 31 wherein the heating elementis an elongated metal tube through which fluid is routed so that fluidcontacts and is heated by both and inside and outside of the metal tube.34. A method for providing a heated cleaning fluid to a vehicle surfacecomprising: a) coupling a source of cleaning fluid to a heating vessel;b) routing a cleaning fluid into an inlet of the heating vessel suchthat the fluid flows from the inlet to an outlet of said vessel; c)heating fluid in the heating vessel as it passes from the inlet to theoutlet; d) directing the fluid from the outlet to a nozzle fordispensing heated fluid against said vehicle surface; and e) activatinga motor in response to the user activating a switch to dispense heatedfluid from a nozzle and provide wiping action of wipers.
 35. The methodof claim 34 wherein a single motor is activated in response to the useractivating a switch, said single motor pumping fluid into the heatingvessel, dispensing heated fluid from a nozzle, and providing motivepower for wiping action of wipers.
 36. The method of claim 35 wherein anoutput from the single motor is coupled to a pump impeller by means of aclutch to allow separate control over pumping of fluid and wiper motion.37. The method of claim 34 comprising coupling an output from a singlemotor to a wiper arm through a reducing gear to produce back and forthmotion of one or more wiper blades.
 38. The method of claim 34 whereinthe vessel comprises a bent metal tube and the heating of fluid in saidtube is performed by energizing the metal tube.
 39. The method of claim34 wherein pumping of fluid is prevented when the wiper arms/blade arenot able to move.